Heart and Stroke Encyclopedia

Knowledge starts here.

Caffeine is in coffee, tea, soft drinks, chocolate and some nuts. Many studies have been done to see if there's a direct link between caffeine, coffee drinking and heart disease. The results are conflicting. This may be due to the way the studies were done and other dietary factors. However, moderate coffee drinking (1-2 cups per day) doesn't seem to be harmful.

Calcium antagonists, also called calcium channel blockers, are drugs that lower blood pressure for people with hypertension. They block the movement of calcium into the heart and blood vessel muscle cells, causing the muscles to relax. This lowers blood pressure, slows the heart rate and decreases oxygen demands of the heart. These drugs also are used to treat other heart conditions, such as chest pain (angina) and abnormal heart rhythms (arrhythmias).

Calcium channel blockers, also called calcium antagonists, are drugs that lower blood pressure for people with hypertension. They block the movement of calcium into the heart and blood vessel muscle cells, causing the muscles to relax. This lowers blood pressure, slows the heart rate and decreases oxygen demands of the heart. These drugs also are used to treat other heart conditions, such as chest pain (angina) and abnormal heart rhythms (arrhythmias).

A carbohydrate is a nutrient in food that is converted into glucose, or sugar, to provide the cells of the body with energy. Carbohydrates include foods with naturally occurring sugars such as whole grains, beans, vegetables and fruits, as well as less healthy foods with added sugars such as cakes, soda and candy.

Cardiac ablation, also sometimes just called ablation, is a therapeutic method used to destroy a small section of heart tissue causing abnormal electrical activity or irregular heartbeat. Ablation is done using electrodes that help identify the site of abnormal activity, then deliver either radiofrequency energy (RF ablation) or intense cold (cryoablation) to destroy the tissue.

Amyloidosis is a group of diseases in which abnormal proteins are deposited in the body’s tissues where they accumulate and replace normal tissue over time. This disease can cause the kidney, heart, liver and gastrointestinal tract or nerves to function poorly and organs to fail. Symptoms include fatigue, shortness of breath, difficulty breathing when lying down, swelling in the ankles and legs, and palpitations.

Cardiac arrest, also known as sudden cardiac arrest, occurs when the heart's electrical system malfunctions and the heart suddenly stops beating ? often without warning. While the terms "sudden cardiac arrest" and "heart attack" are often used as if they are synonyms, they aren't. Sudden cardiac arrest can occur after a heart attack, or during recovery. Heart attacks increase the risk for sudden cardiac arrest, but most heart attacks do not lead to sudden cardiac arrest. Immediate CPR can double or triple the chances of survival from sudden cardiac arrest.

Cardiac catheterization is way of examining the inside of the heart to see how well it is working, identify problems and possibly open blocked arteries. A thin tube called a catheter is inserted into a blood vessel (vein or artery) and threaded into the heart and into the coronary arteries. During cardiac catheterization, doctors can perform an angioplasty and/or insert a stent, which is a tube-like device that props open a previously blocked artery. Cardiac catheterization is used in procedures such as coronary arteriography (also known as angiography) and angioplasty.

Cardiac-computed tomography is an X-ray imaging technique that uses a computer to produce cross-sectional images. Also referred to as computerized axial tomography, or CT, CAT scan, multidetector CT or MDCT, it can be used to examine the heart and blood vessels for problems. It is also used to identify the blood vessels in the brain affected by stroke.

Also called an event recorder.A cardiac event recorder is a battery-powered portable device that you control to tape-record your heart’s electrical activity (ECG) when you have fast or slow heartbeats, or feel dizzy or like you want to faint. It can also be used to see how you respond to medicines.

Cardiac positron emission tomography, also known as a PET scan, is a non-invasive nuclear imaging technique. It uses cross-sectional images and radioactive tracers to evaluate for adequate blood flow to the heart muscle during rest and when the body’s metabolism is activated by the use of the drug dipyridamole. The scans are used to diagnose the extent of coronary artery disease in impacting adequate blood flow.

Cardiac rehabilitation is a professionally supervised program to help people recover from heart attacks or surgery to the heart. Cardiac rehabilation programs usually provide education and counseling services to help survivors increase physical fitness, reduce cardiac symptoms, improve health and reduce the risk of future heart problems.

Cardiac resynchronization, or biventricular pacing, is a treatment for heart failure that uses a pacemaker implanted in the chest. The pacemaker sends tiny electrical impulses to the heart muscle to coordinate the pumping of the chambers of the heart, improving pumping efficiency and reducing the symptoms of heart failure.

Cardiomyopathy is a serious disease in which the heart muscle becomes inflamed and weakened. It may be caused by viral infections, coronary heart disease or diseases involving other organs. Sometimes, the cause of cardiomyopathy is unknown. As the disease worsens, it can lead to heart failure, arrhythmias and heart valve problems.

Cardiomyoplasty is a procedure in which skeletal muscles are taken from a patient's back or abdomen and wrapped around an ailing heart. This added muscle, aided by ongoing stimulation from a device similar to a pacemaker, may boost the heart's pumping motion.

Cardiopulmonary bypass is a procedure to circulate and oxygenate the blood while surgery is performed on the heart. It involves diverting blood from the heart and lungs through a heart/lung machine and returning oxygenated blood to the aorta.

CPR is an emergency lifesaving procedure performed when a person stops breathing or the heart stops beating. It can be performed as Hands-Only? CPR, with rapid compressions on the chest; or it can be performed as chest compressions and mouth-to-mouth breathing. Immediate CPR can double or triple chances of surival after sudden cardiac arrest. The American Heart Association develops CPR guidelines and techniques, and is a leader in CPR training.

Cardiovascular diseases is a term that refers to the entire group of heart and blood vessel diseases. Cardiovascular diseases include heart attack, arrhythmias, atrial fibrillation, and several other conditions.

Cardioversion is the delivery of an electrical shock to a person’s heart to rapidly restore an abnormal heart rhythm (arrhythmia) back to normal. External cardioversion is performed with a defibrillator, either in an emergency situation or as a scheduled treatment for arrhythmia. Internal cardioversion is delivered by a device similar to a pacemaker, called an implantable cardioverter defibrillator.

A caregiver is a person who helps a chronically ill patient cope with an illness. Caregivers can be home healthcare workers, family members or friends. Their responsibilities may range from making sure patients take their medications properly to helping out with day-to-day activities.

Carotid artery disease, also called carotid artery stenosis, is a carotid artery narrowed by a buildup of plaque. Carotid artery disease is a type of atherosclerosis – or hardening of the arteries – is a major risk factor for stroke.

Carotid artery stenosis, also called carotid artery disease, is a carotid artery narrowed by a buildup of plaque. Carotid artery stenosis is a type of atherosclerosis – or hardening of the arteries – is a major risk factor for stroke.

A carotid artery stent is a wire mesh tube used to prop open carotid arteries that becomes narrowed – a condition that can lead to stroke. The carotid artery is a major artery that carries blood from the heart to the brain. After the stent is inserted, it stays in the artery permanently to improve blood flow.

Carotid phonoangiography is a test using a sensitive microphone placed on the neck, very close to the carotid artery. It records sounds and detects blockages, such as those caused by carotid artery disease.

A CAT scan is an X-ray imaging technique that uses a computer to produce cross-sectional images. Also referred to as cardiac-computed tomography, computerized axial tomography, or CT scan, it can be used to examine the heart and blood vessels for problems. It is also used to identify the blood vessels in the brain affected by stroke.

Central agonists are drugs that lower heart rate and reduce blood pressure. They work by preventing the brain from sending signals to the nervous system to speed up the heart rate and narrow the blood vessels. As a result, the heart doesn't pump as hard and blood flows more easily through blood vessels.

Central alpha-agonists are drugs that lower heart rate and reduce blood pressure. They work by preventing the brain from sending signals to the nervous system to speed up the heart rate and narrow the blood vessels. As a result, the heart doesn't pump as hard and blood flows more easily through blood vessels.

Cerebral angiography is a procedure to determine if there is an abnormality of any blood vessels supplying blood circulation to the brain. This test can visualize the arteries or veins of the head and the neck. It determines the part of a blood vessel that has ruptured from an aneurysm or determines the area of abnormality caused by an arterovenious malformation, or AVM.

An embolism occurs when a blood clot or piece of fatty plaque breaks loose and travels through the bloodstream and becomes lodged in a blood vessel and blocks blood flow. When an embolism blocks the flow of blood to the brain, it is called a cerebral embolism, a type of stroke.

A cerebral or brain hemorrhage, also called a hemorrhagic stroke, occurs when a blood vessel or an aneurysm bursts in the brain, causing bleeding inside the brain. A brain hemorrhage can also be caused by a head injury. It is different from a subarachnoid hemorrhage, which occurs when a blood vessel on the brain’s surface ruptures and bleeds into the space between the brain and the skull.

Chest pain can be a warning sign of a heart attack. It can feel like uncomfortable pressure, squeezing or fullness. If you feel this kind of chest pain or other heart attack warning signs, call 9-1-1. Another type of chest pain that occurs during physical activity and subsides with rest is called stable angina. Stable angina can usually be managed with medication, but a heart attack is a medical emergency.

Childhood high blood pressure is hypertension present in teens, children and even babies. As with adults, early diagnosis and treatment can reduce or prevent the harmful consequences. When it comes to blood pressure in children, “normal” is relative and depends on three factors: gender, age and height. Your child’s doctor can tell you what’s right for your child. High blood pressure is typically managed with a heart-healthy diet, regular physical activity and weight management.

About one in three American children is overweight or obese. Obesity in children is determined using age- and sex-specific charts to see how a youngster ranks in percentile compared with others. Childhood obesity can lead to health problems such as high blood pressure, type-2 diabetes and elevated blood cholesterol levels. Obesity in children has also been linked to earlier death in adulthood.

Cholesterol is a soft, waxy substance found among the lipids (fats) in the bloodstream and in all the body's cells. There are several kinds, but the most important are low-density lipoprotein (LDL or "bad") and high-density lipoprotein (HDL or "good"). Too much LDL cholesterol can increase risk for heart disease, stroke and other cardiovascular diseases.

Cholesterol-lowering drugs reduce LDL cholesterol (known as the "bad cholesterol) and increase HDL cholesterol (the "good" kind). These drugs also reduce triglycerides (a blood fat). Several drugs are used to treat cholesterol, including statins. Cholesterol-lowering drugs have been proven to reduce risks for heart disease. Due to potential side effects, patients taking most cholesterol-lowering drugs may need to have periodic liver function tests.

Cholesterol ratio is obtained by dividing the high-density lipoprotein (HDL or “good”) cholesterol level into the total cholesterol. For example, if a person has a total cholesterol of 200 and an HDL cholesterol level of 50, the ratio would be 4:1. The goal is to keep the ratio below 5:1. The optimum ratio is 3.5:1.

Chronic obtrusive pulmonary disease is one of the most common lung diseases. There are two main forms of COPD: chronic bronchitis, which involves a long-term cough with mucus, and emphysema, which involves destruction of the lungs over time. Most people with COPD have a combination of both conditions.

Cigarette smoking is the No. 1 preventable cause of death in the United States and greatly increases the risk of heart disease and stroke. Smokers are likely to have increased blood pressure and decreased ability to exercise, and are more likely to have blood clots.

The stages of heart failure is a rating system to evaluate the development and progression of heart failure symptoms. Developed by the American Heart Association and American College of Cardiology in 2001, the system includes four stages.

Stages A and B represent people who have not yet developed heart failure but are at high risk because of coronary artery disease, high blood pressure, diabetes or other predisposing conditions.

Stage C includes patients with past or current symptoms of heart failure who have a condition called structural heart disease.

Stage D includes patients who have advanced heart failure that is difficult to manage with standard treatment.

Coarctation of the aorta is a congenital heart defect in which the major artery from the heart (aorta) is narrowed somewhere along its length. This obstructs blood flow to the body and increases blood pressure above the constriction.

People who are outdoors in cold weather should avoid sudden exertion. Shoveling snow and even walking through heavy, wet snow or snow drifts can strain your heart. People with coronary heart disease often suffer angina pectoris (chest pain or discomfort) in cold weather. Some studies suggest that harsh winter weather may increase risk of heart attack due to overexertion.

Collateral circulation is the process in which a system of small, normally closed arteries opens up and starts to carry blood to part of the heart when a coronary artery is blocked, or to part of the brain when a cerebral artery is blocked.

Chest compressions are used to manually pump blood through the heart of someone who has suffered sudden cardiac arrest. Compressions are part of Hands-Only CPRŽ, which is recommended for an adult who suddenly collapses outside the hospital. If someone collapses: (1) Call 9-1-1; and (2) Pump hard and fast in the center of the chest at the rate of at least 100 compressions per minute. You may dramatically increase the victim's survival chances. You can sing "Stayin' Alive" to help you keep the right beat.

A computerized axial tomography scan is an X-ray imaging technique that uses a computer to produce cross-sectional images. Also referred to as cardiac-computed tomography, or CT or CAT scan, it can be used to examine the heart and blood vessels for problems. It is also used to identify the blood vessels in the brain affected by stroke.

A congenital heart defect simply means a heart problem that was present at birth. Symptoms can appear immediately or many years later. Congenital heart defects ? also commonly called congenital heart disease ? cause more deaths in the first year of life than any other birth defect.

Also called heart failure, congestive heart failure is when the heart can't pump enough blood to the organs. The heart works, but not as well as it should. Heart failure is almost always a chronic, long-term condition. The older you are, the more common congestive heart failure becomes. Your risk also rises if you are overweight, diabetic, smoke, abuse alcohol or use cocaine. When a heart begins to fail, fluid can pool in the body; this manifests as swelling (edema), usually in the lower legs and ankles. Fluid also may collect in the lungs, causing shortness of breath.

The American Heart Association recommends cooking oils lowest in saturated fats, trans fats and cholesterol – such as canola oil, corn oil, olive oil, safflower oil, sesame oil, soybean oil and sunflower oil. Use them sparingly, though, because they contain 120 calories per tablespoon. Use liquid vegetable oils or nonfat cooking sprays whenever possible. Stay away from coconut oil, palm oil and palm kernel oil. Even though they are vegetable oils and have no cholesterol, they are high in saturated fats.

Also called coronary angiogram, coronary angiography is an X-ray test to diagnose diseases of the arteries that supply blood to the heart. Coronary angiography can detect weakened blood vessel walls and narrowed or blocked vessels. X-rays are taken after a special dye has been injected into the bloodstream, making the vessels and blood flow through the vessels visible on X-rays.

Also called coronary heart disease, coronary artery disease is the most common type of heart disease. It is when plaque builds up in the heart's arteries, a condition called atherosclerosis. As plaque builds up, the arteries narrow, making it more difficult for blood to flow to the heart. If blood flow becomes reduced or blocked, angina (chest pain) or a heart attack may occur. Over time, coronary artery disease can also lead to heart failure and arrhythmias.

Coronary artery spasm is a temporary, sudden narrowing of one of the coronary arteries (the arteries that supply blood to the heart). The spasm slows or stops blood flow through the artery and starves part of the heart of oxygen-rich blood.

Also called coronary artery disease, coronary artery disease is the most common type of heart disease. It is when plaque builds up in the heart's arteries, a condition called atherosclerosis. As plaque builds up, the arteries narrow, making it more difficult for blood to flow to the heart. If blood flow becomes reduced or blocked, angina (chest pain) or a heart attack may occur. Over time, coronary artery disease can also lead to heart failure and arrhythmias.

Coronary microvascular disease (MVD) is heart disease that affects the walls and inner lining of tiny coronary artery blood vessels that branch off from the larger coronary arteries. In coronary MVD, the heart's tiny coronary artery blood vessels do not have plaque, but damage to the inner walls of the blood vessels that can lead to spasms and decrease blood flow to the heart muscle.

CPR (cardiopulmonary resuscitation) is an emergency lifesaving procedure performed when a person stops breathing or the heart stops beating. It can be performed as Hands-Only™ CPR, with rapid compressions on the chest; or it can be performed as chest compressions and mouth-to-mouth breathing. Immediate CPR can double or triple chances of survival after sudden cardiac arrest. The American Heart Association develops CPR guidelines and techniques, and is a leader in CPR training.

Creatinine is created by muscle metabolism breaking down creatine phosphate. Creatinine buildup in the blood can be a warning sign of poor kidney function and cardiovascular disease. This is because the kidneys normally filter it, and kidney problems can be a complication of heart failure. In heart failure the kidneys are less able to dispose of sodium and water, causing fluid retention in the tissues.

Cardiac resynchronization, or biventricular pacing, is a treatment for heart failure that uses a pacemaker implanted in the chest. The pacemaker sends tiny electrical impulses to the heart muscle to coordinate the pumping of the chambers of the heart, improving pumping efficiency and reducing the symptoms of heart failure.

A CT scan is an X-ray imaging technique that uses a computer to produce cross-sectional images. Also referred to as cardiac computed tomography, computerized axial tomography or CAT scan, it can be used to examine the heart and blood vessels for problems. It is also used to identify the blood vessels in the brain affected by stroke.

Cyanosis is a bluish discoloration of the skin or mucous membranes caused by lack of oxygen in the blood. Its root is a Greek word for "blue." Cyanosis is caused when much of the blood circulating through the body is "blue," or oxygen-poor, rather than "red," or oxygen-rich.